Technical Code for Testing of Building Foundation Piles

8/18/2019 Technical Code for Testing of Building Foundation Piles

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National Standard of the People’s Republic of China

Technical Code for Testing of Building Foundation Piles

JGJ 106—2003

Approved by: Ministry of Construction, P.R.China

Implemented from July 1 of 2003

2003 Beijing


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Ministry of Construction, P.R.China

AnnouncementNo.133

Announcement on the Issuance of Technical Code for

Testing of Building Foundation Piles

This is to approve Technical Code for Testing of Building Foundation Piles as industrial

standard (refer. No. JGJ106 —2003) and implement it from July 1 of 2003. In this Code,

Clause 3.1.1, 4.3.5, 4.4.4, 6.4.6, 8.4.7, 9.2.3, 9.2.4, 9.4.2, 9.4.5, 9.4.15 are mandatory

stipulations, which shall be implemented strictly. the previous industrial standard Regulations

for High Strain Dynamic Testing of Foundation Piles (JGJ106 —97) will become invalid at the

same time.

This Code shall be published and distributed by China Architecture Industry Press organized

by the Standard Norm Research Institute of the Ministry of Construction.

Ministry of Construction, P. R. China

March 21, 2003


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Foreword

This Code is laid down the Code Compilation Team according to document (JB[2000]No.284)

issued by the Ministry of Construction after this team has carried out universal investigation

and research, has summed up practical experience and scientific research results of the testing

of foundation piles of domestic and international pipe foundation job, and has collected

universal opinions.

Main technical contents of this Code are as follows: general provisions, terms and symbols,

basic regulations, vertical compression resistance static test of single pile, single pile, vertical

uplift static test & horizontal static test of single pile, core drilling, low strain integrity

testing , high strain dynamic testing , crosshole sonic logging, etc.

The Ministry of Construction shall be responsible for management of this Code and

explanation of mandatory clauses, the compilation institutions shall be responsible for

explanation of technical contents.

Compilation institutions of this Code:: China Academy of Building Research address: 30#,

North Sanhuan Donglu, Beijing; Post Code: 100013

Institutions participating in compilation of this Code:

Guangdong Building Science Research Institute

Shanghai Gangwan Engineering Design & Research Institute

Metallurgical Industry Engineering Quality Supervision Station Testing Center

Wuhan Institute of Rock and Soil Mechanics of Chinese Academy of Sciences


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Shenzhen Survey Research Institute

Building Science Research Institute of Liaoning Province

Building Engineering Quality Examination & Testing Center of Henan Province

Building Science Research Institute of Fujian Province

Building Science Research Institute of Shanghai

Prepared by:

Chen Fan Xu Tianping Zhu Guangyu Zhong Dongbo

Liu Minggui Liu Jinli Ye Wanling Teng Yanjing

Li Dazhan Liu Yanling Guan Lijun Li Rongqiang

Wang Minquan Chen Jiuzhao Zhao Haisheng Liu Chun

Ji Cangjiang


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8.1 Scope of Application ...............................................................................................56

8.2 Instrumentations....................................................................................................56

8.3 On-the-Spot Inspection............................................................................................57

8.4 Analysis and Determination of Measured Data.......................................................59

9. High Strain Dynamic Testing ...............................................................................................63

9.1 Scope of Application ..................................................................................................63

9.2 Equipments.................................................................................................................63

9.3 Site Test ......................................................................................................................64

9.4 Analysis and Determination of the Test Data .............................................................66

10. Cross-hole Sonic Logging..................................................................................................74

10.1 Scope of Apllication ..............................................................................................74

10.2 Equipments............................................................................................................74

10.3 Site Test ....................................................................................................................75

10.4 Analysis and Determination of the Test Data ...........................................................76

Appendix A Endogenetic Force Test on the Pile Body..........................................................84Appendix B Treatment of Pile Toe of Concrete Pile .............................................................91

Appendix C Static Load Test Record Form...........................................................................92

Appendix D Records of Core Extraction Test .......................................................................94

Appendix E Core Sample Processing and Measuring..............................................................97

Appendix F Installation of Stress Sensor .................................................................................99

Appendix G Trial Pile Driving and Monitoring of Pile Driving ............................................101

G.1 Trial Pile Driving .....................................................................................................101

G.2 Monitoring of Hammering Stress of Pile Body .......................................................102

G.3 Monitoring of Hammering Energy........................................................................103

Appendix H Points of Burying Sound Ranging Pipes.........................................................104

Terminology in the Code................................................................................................105


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1. General Provisions

1.0.1 In order to ensure work quality of testing of foundation piles, unify the testing of

foundation piles, provide reliable reference for design and construction acceptance,

make quality testing of foundation piles meet requirements of “safe, applicable,

advanced in technique, exact data and correct assessment, this Code is hereby drafted.

1.0.2 This Code is applicable for testing and assessment of the bearing capacity and the pile

integrity of foundation piles of construction projects.

1.0.3 Method for testing of foundation piles shall make reasonable selection and allocation

after considering such factors geologic condition, pile type and reliability of

construction quality, requirement for use according to features and applicable scopes

of all kinds of testing methods. Result of testing of foundation piles shall be

analyzed and determined according to the aforesaid factors.

1.0.4 Quality testing of foundation piles of construction projects shall execute this Code and

shall meet regulations of the state’s existing relevant compulsory standards.


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2. Terms and Symbols

2.1 Terms

2.1.1 Foundation Pile

Individual pile in pile foundation.

2.1.2 Pi1e Integrity

It reflects relative change of overall stationarity indices of shaft section size,

compactness of shaft material and continuity.

2.1.3 Pile Defects

a general designation of some phenomena such as shaft break, split, ;necking effect ,

slurry clamp sundries , hollow hole, honeycomb, unconsolidation, which can

deteriorate shaft integrality and cause reduction of shaft structure strength and

durability.

2.1.4 Static loading test

Vertical pressure or vertical upward pulling force or horizontal thrust shall be exerted

stage by stage on pile top, operator shall observe sedimentation occurring on the pipe

top along with the time, lift up displacement or horizontal displacement, in order to

determine test methods for vertical compression resistance bearing capacity of

relevant single pile, vertical uplift bearing capacity of single pile or horizontal bearing

capacity of single pile.

2.1.5 Core drilling method

A method to test the pile length, shaft defect, dreg thickness of pile toe, strength,

compactness and continuity of shaft concrete through drilling core sample by driller,


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in order to determine rock and soil characters of pile end.

2.1.6 Low strain integrity testing

A testing method, in which, operator shall carry out an excitation on pile top by using

a low energy transient state or stable state excitation mode, measure velocity time

interval curve or velocity admittance curve of pile top, in order to determine shaft

integrality through wave movement theory analysis or frequency domain analysis.

2.1.7 High strain dynamic testing

A testing methods, in which, operator shall shock pile top by using thumper, measure

velocity and time interval curve of force of pile top, in order to determine vertical

compression resistance bearing capacity and shaft integrality of single pile through

wave movement theory analysis.

2.1.8 Crosshole sonic logging

A testing methods, in which, testing is carried on shaft integrality by transmitting and

accepting the sound wave among the embedded sound logging pipe through relative

changes of some acoustic parameters actually measured sound time, frequency and

amplitude attenuation, which is spread by sound wave in medium of concrete.


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2.2 Symbols

2.2.1 Resistance and material property

c ——Unidimensional stress velocity of wave spread of shaft abbr. wave velocity of

shaft ;

E ——elastic modulus of shaft materials;

cu f ——compressive strength of concrete core sample;

m —— proportion factor of horizontal reaction coefficient of foundation soil;

uQ ——ultimate bearing capacity of vertical compression resistance of single pile;

a R ——characteristic value of vertical compression resistance bearing capacity of single

pile;

c R ——vertical compression resistance bearing capacity of single pile determined by

Case Method;

x R —— test estimated value of soil resistance of the aforesaid parts;

v ——sound velocity of concrete shaft;

Z ——mechanical impedance of shaft section;

p ——shaft material mass density;

2.2.2 Action and action effect

F ——hammer force;

H ——horizontal force acting on the ground in horizontal static test of single pile;

p —— failure load measured from compression resistance test of core sample;


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Q ——Vertical load and shaft axis in static test of vertical compression resistance of

single pile;

s ——vertical sedimentation of pile top and vertical displacement of shaft;

U ——upwards withdrawing load exerted in static test of vertical anti-withdraw of single

pile;

V ——movement velocity of particle ;

oY ——horizontal displacement of horizontal forceaction point ;

δ ——uplift volume of pile top;

sσ ——reinforcement stress.

2.2.3 Geometric Parameter

A——shaft section area;

B——margin of rectangular pile;

ob ——calculation width of shaft;

D——shaft diameter outer diameter ;

d ——average diameter of core sample;I——conversion section moment of inertia of shaft;

l ′——clear distance of outer wall of both sound logging pipes of each testing section;

L—— length of lower pile at survey point;

x——distance between sensor installation point and shaft defect;

z——depth of survey point

2.2.4 Calculation coefficient

c J ——damp coefficient of Case Method;

α ——horizontal deformation coefficient of pile;


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β ——shaft integrity coefficient of high strain dynamic testing;

λ ——coefficient corresponding to different statistical quantity in sample;

yv ——horizontal displacement coefficient of pile top;

ξ ——conversion coefficient of compressive strength concrete core sample.

2.2.5 Other

m A ——sound wave amplitude average value;

p A ——sound wave amplitude value;

a ——value voltage of head wave peak of signal;

oa —— peak value voltage of zero decibel signal;

mc ——average value of wave velocity of shaft;

f —— basic frequency of frequency and sound wave signal;

n ——quantity and sample quantity;

xs ——standard deviation;

T ——signal cycle;

t ′ ——corrected value of sound logging pipe and coupling the sound time of water layer;

ot ——delay time of instrumentations system;

1t —— time corresponding to the first peak of velocity;

ct ——sound time;

it ——measured value of time and sound time;

r t ——ascending time of hammer force;


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xt —— time corresponding to defect echo peak;

ov ——abnormal judgment value of sound velocity;

cv ——critical value of abnormal judgment of sound velocity;

Lv —— lower limit value of sound velocity;

mv ——average value of sound velocity;

f Δ —— lower limit among neighboring resonance peaks of pile toe on amplitude

frequency curve;

f ′Δ ——frequency difference among defect neighboring resonance peaks on amplitude

frequency curve;

T Δ —— time difference among the first peak of velocity wave and echo wave peak of

pile toe;

xt Δ —— time difference between the first peak of velocity wave and defect echo wave

peak.


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3. Basic Regulations

3.1. Testing Methods & Contents

3.1.1 Bearing capacity& shaft integrity sampling testing of single pile shall be carried

out on engineering piles.

3.1.2 Testing methods for foundation pile shall be chosen according to 3.1.2. on the basis of

testing aim.

Form 3.1.2 Testing Method & Testing Aim

Testing Method Testing Aim

Vertical compressionresistance static testof single pile

Determine vertical compression resistance ultimate bearing capacity ofsingle pileDetermine whether vertical compression resistance bearing capacitymeets requirement of design.Determine resistance of pile side and pile end through shaft internalforce and deformation testing;Verify vertical compression resistance bearing capacity testing results ofsingle pile of high strain dynamic testing.

Vertical uplift statictest of single pile

Determine vertical anti-draw ultimate bearing capacity of single pileDetermine whether vertical uplift bearing capacity can meet design.Determine uplift friction resistance of pile through shaft internal forceand deformation testing,

Horizontal static testof integrity

Determine horizontal critical and ultimate bearing capacity of single pile to conclude soil resistance parameters.Determine whether horizontal bearing capacity can meet design.

Determine bending moment of shaft through shaft internal force anddeformation testing.

Core drilling Test cast-in-place pile length, shaft concrete strength, dreg thicknessof pile toe, judge or identify rock and soil character of pile end,determine shaft integrity type.


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Low strain integritytesting

Testing shaft defect and its position, determine shaft integrity type

High strain dynamictesting

Determine whether vertical compression resistance bearing capacity ofsingle pile can meet design;

Test the shaft defect and its position, determine shaft integrity typeAnalyze pile side and soil resistance of pile end

Crosshole soniclogging

Test the shaft defect of cast-in-place pile and its position, determineshaft integrity type.

3.1.3 Shaft integrity testing shall adopts two kinds or many kinds of proper testing method.

3.1.4 Foundation pile testing shall be executed before and after construction, and shall meet

testing method in this Code or other testing method in processional acceptance code,

testing shall be done during pile foundation construction process, quality control of

construction process shall be strengthened.


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3.2 Testing Procedures

3.2.1 Procedure of testing work shall be executed according to Fig 3.2.1:

Fig. 3.2.1 Diagram of Testing Procedure

3.2.2 Investigation, data collection phase shall include the following:

1 Collect rock engineering survey data, pipe foundation design drawings and construction

records of the testing job; understand abnormal situation occurring in construction

Receiving the entrust

InvestigationData collection

Prepare testingscheme

Preparation in earlierstage

On-the-spotInspection

Calculation analysis and resultsappraisal

Testing report

Verification ofinstrumentations

Reinspection, verification, expansionof testing


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process.

2 Further explicate concrete requirement of the entrusting party.

3 Feasibility for implementation of the testing project on site.

3.2.3 According to investigation results and determined testing aim , operator shall choose

testing method, lay down testing scheme. Testing scheme shall contain the following

contents: job summary, standard for testing method and its reference, sampling scheme,

machines or labor needed, test cycle.

3.2.4 Instruments shall be checked and debugged before testing.

3.2.5 Measuring instruments for testing must be in validity period of metrological

verification .

3.2.6 The starting time for testing shall meet the following regulations:

1 When low strain integrity testing or crosshole sonic logging testing is adopted,

concrete strength of testing pile shall amount to at least 70% of design strength, and

shall not be less than 15MPa.

2 When core drilling testing is adopted, concrete age of the testing pile shall be 28d or

strength of preset curing sample under same conditions shall meet the designed

strength.

3 Quiescent time of the bearing capacity testing shall meet concrete strength stipulated in

the above Clause 2, if no mature local experience, time shall not be less than the time in

Form 3.2.6.


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Form 3.2.6 Quiescent Time

Type of Soil quiescent time d

Sandy soil 7

Silty soil 10

Non-saturated 15Glutinous soil

Saturated 25

Note: for mortar-wall cast-in-place pile, quiescent time shall be delayed properly.

3.2.7 After construction, shaft integrity testing of job pile shall be done firstly, then bearing

capacity testing shall be followed. When foundation buried depth is bigger, shaft

integrity testing shall be done at the time of excavation of foundation pit up to

elevation of base.

3.2.8 Testing on site shall follow this Code and stipulations of safe production of the state. If

operational environment on site is not in conformity with requirements for use of

instrumentations, effective protection measures shall be taken.

3.2.9 When abnormal testing data are found, reasons shall be searched for re-testing .

3.2.10 Further verification or testing shall be confirmed by authorities concerned and shall be

executed according to Clause 3.4.1-3.4.7 of this Code.

3.3 Testing Quantity

3.3.1 If required by design, or in case of one of the following conditions, static test shall be

adopted before construction for confirmation of bearing capacity characteristic value of

vertical compression resistance of single pile:


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1 Pipe foundation with design grade A or B;;

2 Complicated geographical conditions and low reliability of construction quality of

pile;

3 New pile type or new technology adopted in this region.

Testing quantity shall not be less than 3 pieces under same conditions, and shall not be

less than 1% of total quantity of pile; and shall less than 2 pieces when total quantity of

job pile is below 50 pieces.

3.3.2 If driven prefabricated pile meets one of the following conditions, high strain dynamic

testing shall be adopted for the purpose of process monitoring of trial piling:

1 Control the shaft stress during piling process;

2 Choose instrument for driving pile and confirm technology parameters;

3 Choose end bearing layer of pile.

With same construction technology and similar geographical conditions, piling

quantity shall not be less than 3 pieces.

3.3.3 The testing pile selection for single pile bearing capacity and shaft integrity

acceptance sampling testing shall meet the following regulations:

1 Pile with defective construction quality;

2 Important pile, in designer’s opinion;

3 Pile with abnormal partial geographical conditions;

4 Pile with different construction technology;

5 In case of bearing capacity acceptance testing, type- Ⅲ pile determined in properly

chosen integrity testing ;

6 Besides the aforesaid regulations, pile of the same type shall be distributed uniformly

at random.

3.3.4 Selective examination quantity of shaft integrity testing of concrete pile shall meet the


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following regulations:

1 Pile quantity for selective examination of pile cap of three piles under column or

below the three pipes shall not be less than one piece.

2 For cast-in-place pile with design grade- A, or complicated geographical conditions, or

lower reliability of pile quality, selective examination quantity shall not be less than

30% of total pile quantity, and shall not be less than 20 pieces; selective examination

quantity of other pipe foundation job shall not be less than 20% of total pile quantity,

and shall not be less than 10 pieces.

Note: 1.For end-support-type big-diameter cast-in-place pile, operator shall choose core

drilling or crosshole sonic logging within the scope of aforesaid selective

examination pile quantity to carry out shaft integrity testing on some testing piles.

Selective examination quantity shall not be less than 10% of total pile quantity.

2. For piles with artificially excavated bores on pile end bearing layer above

groundwater level and after telotremata, which have been examined and verified,

and, for single section of concrete-prefabricated pile, selective examination quantity

can be reduced properly, but it shall not be less than 10% of total pile quantity, shall

not be less than 10 pieces.

3. When pile quantity meeting stipulation of paragraph 1-4 of Clause 3.3.3 is more, or

in order to understand shaft integrity situation of the whole job foundation pile,

selective examination quantity shall be increased properly.

3.3.5 If job pile within unit job and under same condition meets one of the following

conditions, static test of vertical compression resistance bearing capacity of single

pile shall be adopted for the purpose of acceptance testing :

1. Pipe foundation with design grade A;

2. Complicated geographical conditions, low reliability of pile construction quality;


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3. New pile type or new technology adopted in this region;

4. Construction of soil-compacting pile group produces compacting effect.

Selective examination quantity shall not be less than l% of total pile quantity, and shall

not be less than 3 pieces; and shall not be less than 2 pieces when total pile quantity is

within 50 pieces.

Note: For job pile out of the aforesaid Clause 1-4, when vertical compression resistance static test is

adopted for the purpose of acceptance of bearing capacity testing, selective examination quantity shall be

executed according this regulation.

3.3.6 For prefabricated pile out of Clause 3.3.5 and for cast-in-place pile which meets

applicable testing scope of high strain dynamic testing, high strain dynamic testing can

be adopted for the purpose of acceptance testing of vertical compression resistance

bearing capacity of single pile. When compared verification data under similar

conditions in local region are available, high strain dynamic testing can also become a

supplementation acceptance testing of vertical compression resistance bearing capacity

of single pile, as stipulated in Clause 3.3.5.Selective examination quantity shall not be

less than 5% of total pile quantity and shall not be less than 5 pieces.

3.3.7 For end-support-type big-diameter cast-in-place pile, when vertical compression

resistance bearing capacity of single pile fails to be tested due to limit by instrument or

site condition,, core drilling can be adopted for determination of dreg thickness at pile toe,

and core sample of pile end bearing layer can be drilled and taken for the purpose of

examination of pile end bearing layer. Selective examination quantity shall not be less

than 10% of total pile quantity and shall not be less than 10 pieces.

3.3.8 For pipe foundation that bears bigger pulling force and horizontal force, vertical

anti-pulling and horizontal bearing capacity testing of single pile shall be done. Testing

quantity shall not be less than l% of total pile quantity, and shall not be less than 3 pieces.


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3.5 Testing Results Evaluation And Testing Report

3.5.1 Appraisal of shaft integrity testing results shall provide shaft integrity type of every

piece of testing pile. Classification of shaft integrity shall meet Form 3.5.1 and shall be

classified according to technical contents stipulated in Chapter 7-10 of this Code.

Form 3.5.1 Classification of Shaft Integrity

Type of Shaft Integrity Principles for Classification

Type-I pile Shaft in completeType-II pile Slight defect exists in shaft, which will not affect normal function

of shaft structure bearing capacity.

Type- Ⅲ pile Obvious defect in shaft has an influence on shaft structure bearing

capacity.

Type-Ⅳ pile Serious defect exists in shaft

3.5.2 Type- Ⅳ pile shall be subject to job treatment.

3.5.3 Evaluation of bearing capacity testing results of job pile shall give testing value of

bearing capacity for each piece of testing pile, and give results whether bearing

capacity characteristic value of single pile of unit job under same condition design

meets requirement.

3.5.4 Testing report shall contain exact results and standard words and expresses.

3.5.5 Testing report shall include the following contents:

1. Name of the entrusting party, name of job, place, construction, survey, design,

supervising unit and construction unit, foundation, structure type, quantity of layer,


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design requirement, testing aim, testing reference, testing quantity, testing date;

2. Description of geographical conditions;

3. Pile serial number, pile position and relevant construction records of testing pile;

4. Statement of testing method, testing instrumentations, testing process;

5. Testing data, measurement and calculation/analysis curve, form and summary result of

testing pile;

6. Testing results relating to testing contents.

3.6 Testing Institution & Testing Personnel

3.6.1 Testing institution shall be subject to measurement certification and have qualification

of foundation pile testing.

3.6.2 Testing personnel shall be qualified after being trained and have relevant qualification.


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4. Static Test of Vertical Compression Resistance of Single

Pile

4.1 Scope of Application

4.1.1 This method is applicable for vertical compression resistance bearing capacity of

testing pile.

4.1.2 If sensor or displacement pole for measurement of shaft stress, strain, pile toe

counterforce is embedded, layered side resistance and end resistance of pile or

displacement of shaft section can be measured.

4.1.3 If test pile is provided as a reference for the design, the pile shall be loaded until being

destroyed; bearing capacity of pile is controlled by shaft strength, the loading volume

required in the design shall be applicable.

4.1.4 When job pile sample is tested, loading volume shall not be less than design the

required bearing capacity characteristic value of single pile by 2.0 times.

4.2 Instrumentations and Installation

4.2.1 Test loading shall adopt oil jack. When two and more sets of jacks are used for loading,

parallel connection and synchronous work are required, and the following regulations

shall be met.


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1. Jack mode and specification to be used shall be the same.

2. Composite force of jack shall be superposed with pile axes.

4.2.2 Loading counterforce device may be crossbeam counterforce device of anchor pile

according to site condition, mould weight platform counterforce device, mould weight

counterforce device of anchor pile, earth anchor counterforce device, and shall meet

the following regulations:

1. Counterforce that can be provided by the loading counterforce device shall not be less

than maximum loading volume by 1.2 times.

2. Operator shall carry out a strength and deformation calculation on all members of

loading counterforce device.

3. Operator shall calculate anchor pile anti-pulling force foundation soil, uplift

reinforcement, pile joint ; when job pile is used as anchor pile, anchor pile quantity

shall not be less than 4 pieces, and shall monitor uplift volume of anchor pile.

4. Mould weight shall be enough before testing and shall be placed on platform stably .

5. Stress of mould weight exerted on substrate shall not bigger than 1.5 times of bearing

capacity characteristic value of substrate, if applicable, job pile shall be used as stacking

pivot.

4.2.3 Load measurement can be determined directly by load sensor which is put on the jack;

or pressure meter or pressure sensor which is in parallel connection with jack oilway

shall be adopted to determine oil pressure, curve conversion load shall be determined

according to jack rate. Measurement error of sensor shall not be more than 1%,

accuracy of pressure meter shall be superior or equal level 0.4. Pressure of pressure

meter, oil pump, oil tube used for test in case of maximum loading shall not exceed

80% of specified working pressure.

4.2.4 Sedimentation measurement shall adopt displacement sensor or wide range dial


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indicator, and shall meet the following regulations:

1. Measurement error shall not be more than 0.1% FS, resolution is superior to or equal to

0.01mm.

2. Pile with diameter or margin of more than 500 mm shall be equipped with four

displacement testing meters symmetrically on its two directions, Pile with diameter or

margin of less than or equal to 500mm shall be equipped with two displacement testing

meters.

3. The testing surface of sedimentation shall be at a position 200mm below the pile top,

survey point shall be fixed on shaft firmly.

4. Datum beam shall have a certain rigidity, one end of beam end shall be fixed on datum

pile, another end shall be erected on datum pile simply.

5. Holder for fixing and supporting displacement meter dial indicator and datum beam

shall avoid influences caused by air temperature, vibration and other factors.

4.2.5 Center distance between testing pile, anchor pile supporting pier side of mould weight

platform and datum pile shall meet Form 4.2.5.


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Form 4.2.5 Center distance between testing pile, anchor pile(supporting pier side of

mould weight platform) and datum pile

Distance

counterforce

device

Testing pile center and

anchor pile center

(or supporting pier side of

mould weight platform)

Testing pile center and

datum pile center

Datum pile center and

anchor pile center

(or supporting pier side of

mould weight platform)

Anchor pile

crossbeam

≥ 4(3)D and 2.0m ≥ 4(3)D and 2.0m ≥ 4(3)D and 2.0m

Mould weight

platform

≥ 4D and 2.0m ≥ 4(3)D and 2.0m ≥ 4D and 2.0m

earth anchor device ≥ 4D and 2.0m ≥ 4(3)D and 2.0m ≥ 4D and 2.0m

Note: 1. D is testing pile, anchor pile or design diameter or margin of earth anchor, the larger value is bigger.

2. In case of testing pile or cap-shape guttate or multiple tray decoration, center distance of testing pile and

anchor pile shall not be less than 2 times of expanded end diameter.

3. Values in bracket can be used for such circumstance that designed pile center distance of several rows of piles

is less than 4D in case of job pile acceptance testing

4. For soft soil stockyard, when weight is enlarged, distance between support pier side and datum pile center and

testing pile center shall be increased, vertical displacement of datum pile shall be observed in experiment

process.

4.2.6 When testing of pile side resistance and pile end resistance is required, sensor

embedded in shaft shall be executed in Annex A of this Code.


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measure and read once every 30 minutes.

2. Relatively stable standard of the testing pile sedimentation: sedimentation volume of

pile top within every one hour shall not exceed 0.1mm, and shall occur for twice

continuously from 30 th minute after the grading load is exerted, the result shall be

calculated according to sedimentation value observed for three times every 30 minutes

within 1.5 hour .

3. When sedimentation velocity of pile top has reached relatively stable, load of the next

grade can be exerted.

4. In case of unloading, load of every level shall be maintained for one hour, after operator

measures and reads sedimentation volume of pile top according to 15, 30 and 60

minutes, unloading of the next level can be executed. After unloading to zero, operator

shall measure and read the remaining sedimentation volume of pile top, maintenance

time is 3 hours, measuring and reading time shall be 15 and 30mins, operator shall

measure and read once every 30 minutes.

4.3.7 After construction of job pile, low-speed maintenance load testing method shall be

adopted for acceptance testing. When mature local experience is available, high-speed

maintenance load testing method can be used.

Maintenance time of high-speed maintenance load testing method of load of every level

shall be at least one hour, whether delay maintenance load time shall be determined

according to pile top sedimentation convergence situation.

4.3.8 In case of the following circumstances, loading can be terminated:

1. Under load action at a certain level, sedimentation volume of pile top is more than 5

times of sedimentation volume under load action of previous level.

Note: When sedimentation of pile top can be stable and total sedimentation volume is less than 40mm,

it shall be loaded till total sedimentation volume of pile top is more than 40mm.


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2. Under load action of a certain level, if sedimentation volume of pile top is more than 2

times of sedimentation volume under load action of previous level, and has not reached

relatively stable standard after 24 hours.

3. It has reached maximum loading volume required by design.

4. When job pile is used as a anchor pile, uplift volume of anchor pile has reached

allowable value.

5. When load sedimentation curve presents a slow change shape, it can be loaded till total

sedimentation volume of pile top reaches 60 80mm; under special circumstance, it

can be loaded according to detailed demands until the accumulated sedimentation

volume of pile top is more than 80mm.

4.3.9 Testing data shall be recorded according to format of Form C.0.1 of Annex c of this

Code.

4.3.10 When testing the pile side resistance and pile end resistance, measuring and reading

time of the testing data shall meet Clause 4.3.6 .

4.4 Analysis and Determination of Testing Data

4.4.1 Clearing-up of testing data shall meet the following regulations:

1. When determining vertical compression resistance bearing capacity of single pile,

operator shall draw relation curve of vertical load vs sedimentation Q-S),

sedimentation vs logarithm of time t s lg− , if necessary, operator shall also draw

curve necessary for other auxiliary analysis.

2. When carrying out shaft stress, strain and pile toe counterforce, operator shall clear up


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record form of relevant data, and draw shaft axis distribution diagram according to

Annex A of this Code, and calculate layered side friction resistance and end resistance

value of different soil layer.

4.4.2 Limit bearing capacity uQ of vertical compression resistance of single pile can be

determined according to the following method after comprehensive analysis:

1. It can be determined according to characteristics that sedimentation changes along with

load: For rapid-rise Q-s curve, operator shall take load value corresponding to starting

point and ending point where obvious rapid rise occurs.

2. It can be determined according to characteristics that sedimentation changes along with

time: operator shall take load value of previous level where obvious downward bend

occurs at t s lg− curve tail.

3. In case of circumstances occurring in Paragraph 2 of Clause 4.3.8 , operator shall take

load value of previous level.

4. For slowly changed Q-s curve, operator shall load value corresponding to S 40mm

according to sedimentation volume; when pile length is more than 40m, elastic

compression of shaft shall be considered; For pile with diameter more than or equal to

800mm, load value corresponding to s=0.05D D is pile end diameter shall be taken.

Note: when vertical compression resistance bearing capacity which is used for determining the pile

according to the aforesaid Clause IV does not reach limit, maximum test load value shall be taken

for limit bearing capacity of vertical compression resistance of pile.

4.4.3 The counting value limit bearing capacity of vertical compression resistance of single

pile shall be determined according to the following regulations:1. For the testing pile results participating in counting, when its range does not exceed

30% of average value, average value shall be taken as limit bearing capacity of vertical


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compression resistance of single pile.

2. When range exceeds 30% of average value, reason of oversize range shall be analyzed,

the result shall be determined according to situation of job, if necessary, the testing pile

quantity can be increased.

3. For pile cap under column with pile quantity of 3 pieces or below, selective

examination quantity of job pile is not less than 3 pieces, lower value shall be taken.

4.4.4 Value of the bearing capacity characteristic value a R of vertical compression

resistance of single pile in unit job under same condition shall be taken according to 1/2

(0.5 times) of the counting value of limit bearing capacity of vertical compression

resistance of single pile.

4.4.5 The testing report shall include contents of Clause 3.5.5 of this Code and shall include:

1. Geologic log corresponding to pile position of testing pile;

2. Size of testing pile and anchor pile, material strength, anchor pile quantity,

reinforcement arrangement;

3. The loading counterforce type and stacking method shall indicate stacking weight,

anchor pile testing method shall have counterforce beam layout;4. Load/download method, load grading;

5. Curve and relevant data form; and curve and data for determining the bearing capacity,

required by this Code 4.4.1

6. Reference for determining the bearing capacity;

7. In case of testing the hierarchical friction resistance, sensor type installation position,

axis calculation method, change curve of shaft axis under all levels of loads, pile side

limit friction resistance and pile end resistance of each soil layer shall be available,


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2. When natural substrate is adopted to provide counterforce, stress exerted on substrate

shall not exceed 1.5 times of bearing capacity characteristic value of substrate; pivot

center of gravity of counterforce beam shall be superposed with pedestal center.

5.2.3 Technical requirement of load measurement and instrumentations shall meet Clause

4.2.3 of this Code.

5.2.4 Technical requirement uplift volume measurement of pile top and its apparatus shall

meet Clause 4.2.4 of this Code.

Note: Observation point of uplift volume of pile top can be fixed on shaft concrete of pile top

surface.

5.2.5 Center distance among test pile, pedestal and datum pile shall meet Form 4.2.5.

5.2.6 When uplift friction resistance distribution of pile side or uplift displacement of pile

end is required to be tested, sensor embedded in shaft or displacement pole embedded

at pile end shall be executed according to Annex A of this Code.

5.3 On-the-spot Testing

5.3.1 For concrete cast-in-place pile and prefabricated pile with joint, low strain

integrity testing shall be adopted for testing the shaft integrity of pile before uplift test.

When construction of uplift cast-in-place pile which is provided as a reference of

design shall be subject to pore forming quality testing, if pile with obvious hole

enlargement is found in middle or lower part of shaft shall not used as uplift test pile;

for prefabricated pile with joint, joint strength shall be calculated.

5.3.2 Low-speed maintenance load testing shall be applicable for vertical uplift static test of


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single pile. If necessary, multiple cycle load/unload testing method can also be adopted.

Load/unload classification of low-speed maintenance load testing method, test method

and stability standard shall be executed according to Clause 4.3.4 and 4.3.6 of this

Code, crack of shaft concrete shall be observed carefully.

5.3.3 In case of the following circumstances, loading can be terminated:

1. Under action of load at a certain level, uplift volume of pile top is bigger than uplift

volume under uplift load action of the previous level by 5 times.

2. If it is controlled according to uplift volume of pile top, when accumulated uplift

volume of pile top is more than 100mm.

3. If it is controlled according to reinforcement tensile strength, when uplift load of pile

top is up to 0.9 times of reinforcement strength standard value.

4. For job pile of acceptance sampling testing, when it is up to maximum uplift load value

required by design.

5.3.4 Testing data shall be recorded according to Format C.0.1 in Annex C of this Code .

5.3.5 Side uplift resistance of the testing pile or uplift displacement of pile end, measuring

and reading time of data shall meet regulations of Clause 4.3.6 of the Code.

5.4 Analysis and Determination of Testing Data

5.4.1 For clear up data, operator shall draw uplift load vs uplift volume ( δ −U )of pile top

relation curve and uplift volume of pile top-logarithm of time( t s lg− )relation curve.

5.4.2 Vertical anti-uplift limit bearing capacity of single pile can be determine according to

the following method:


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1. It is determined according to characteristics that uplift volume changes along with load:

For rapid-rise δ −U curve, load value corresponding to the starting/ending point for

rapid rise;

2. It is determined according to characteristics that uplift volume changes along with time:

operator shall take load value of previous level of obvious bend curve tail or obvious

rapid rise of slope of t s lg− curve.

3. When uplift reinforcement breaks under load at a certain level, operator shall take load

value of previous level.

5.4.3 Determinations of counting value of vertical uplift limit bearing capacity of single pile

shall comply with Clause 4.4.3 of the Code.

5.4.4 When testing pile used as acceptance sampling testing under maximum uplift load

action, if paragraph 3 listed in Clause 5.4.2 of this Code does not occur, the value can

be determined according to design.

5.4.5 Value of vertical uplift bearing capacity characteristic value of single pile of unit job

under same condition shall be taken according to one second (0.5 times) of counting

value of vertical uplift limit bearing capacity of single pile. Note: when job pile does not allow crack in job, load at the previous level of shaft crack as vertical uplift

bearing capacity characteristic value of single pile is taken. Compared with bearing capacity

characteristic value determined according to one second (0.5 times) of limit load value, smaller

value shall be taken.

5.4.6 The testing report shall include contents of Clause 3.5.5 of this Code and also include:

1. Geologic log corresponding to testing pile position;

2. Testing pile size cast-in-place pile shall indicate aperture curve and reinforcement

fixing situation;

3. Load/download method, load grading;


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4. Curve and relevant data form required to be drawn by Clause 5.4.1;

5. Reference for determining the bearing capacity;

6. When uplift friction resistance testing is carried out, sensor type, installation position,

axis calculation method, change curve of shaft axis under load of each level, uplift limit

friction resistance in each soil layer shall be available.


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6. Horizontal Static Load Test of Single Pile


6.1.1 This method is applicable for Single pile horizontal static load test when pile top is

free; please refer to horizontal static load tests in other forms.

6.1.2 This method is applicable for testing horizontal bearing capacity of single pile, so as to

conclude proportion factor of foundation soil reaction coefficient.

6.1.3 Sensor for measuring shaft strain has been embedded, shaft stress under the

corresponding horizontal load action can be measured, and hence bending moment

of shaft shall be calculated.

6.1.4 Test pile provided as an reference for design shall be loaded until larger horizontal

displacement or shaft structure occurring in pile top; for sampling testing of

engineering pile, loading can be controlled according to horizontal displacement

allowable value required by design.

6.2 Instrumentation and Installation

6.2.1 Oil jack shall be used in loading device with horizontal thrust, loading capacity shall not

be less than 1.2 times of maximum test load.

6.2.2 Counterforce of horizontal thrust can be provided by neighboring pile; when

counterforce structure is designed exclusively, its bearing capacity and rigidity shall be

1.2 times of that of test pile.


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6.2.3 Technical requirements of load measurement and its instrumentations shall meet Clause

4.2.3 of this Code; horizontal force action point shall be consistent with actual

engineering elevation of bottom surface of pile cap of pile foundation; jack and test pile

contact surface shall be equipped with spherical bearing, acting force of jack shall pass

through shaft axes horizontally; contact surface between jack and test pile shall be

bolstered up.

6.2.4 Technical requirements for horizontal displacement measurement of pile and its

instrumentations shall meet Clause 4.2.4 of this Code. On both sides of test pile of

action plane of horizontal force shall be provided with two symmetrical displacement

meter installation; when measuring pile is needed to extrude outer corner, two

displacement meters shall also be installed symmetrically on both sides test pile, which

is 50cm above horizontal force action surface.

6.2.5 Datum mark of displacement measurement shall be set without any influence by test and

other factors, datum mark shall be set on the side of test pile which is opposite to

displacement direction and is vertical with acting force direction, clear distance between

datum mark and test pile shall not be less than of pile diameter by 1 time.

6.2.6 In case of measurement of shaft stress or strain, measurement sensor of each testing

section shall be arranged symmetrically, along stress direction, on tensioned and

pressed main reinforcement which is far away neutral axis; inclination between

longitudinal section of the embedded sensor and stress direction shall not more than 10

° . Test section of main underground stress part with 10 times of pile diameter pile

width shall be thickened, clearance between sections shall not more than pile diameter

by one time; if the clearance is more than this depth, clearance of test section can be

enlarged properly. Sensor shall be embedded in shaft according to Annex A of this

Code.


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6.3 On-the-Spot Inspection

6.3.1 Loading method shall be unilateral multi-cycle loading method or low-speed maintained

load method stipulated in Chapter Four of this Code according to actual stress

characteristics of engineering pile, other loading methods can also be adopted

according to design requirements. Test pile which needs measurement of shaft stress or

strain shall adopt maintenance load method.

6.3.2 Test load/unload mode and horizontal displacement measurement shall meet the

following regulations:

1. Grading load of unilateral multi-cycle loading method shall less than estimated 1/10 of

bearing capacity of horizontal limit or maximum test load. After applying load at every

level, operator shall measure and read horizontal displacement after executing dead load

for 4 minutes, and then unload to zero, stop for 2 minutes, measure and read remaining

horizontal displacement, thus a load/unload cycle can be completed, execute this cycle

for 5 times. Displacement observation of grade-I load shall be completed. Test shall not

be paused.

2. Load/unload grading, test method and stabilization standard of low-speed maintenance

load method shall be executed according to Clause 4.3.4 and 4.3.6 of this Code.

6.3.3 In case of one of the following circumstances, loading can be stopped:

1. Shaft breaks off;

2. Horizontal displacement is more than 30 40mm 40mm for soft soil ;

3. Horizontal displacement meets allowable value of horizontal displacement required by

design.

6.3.4 Measured Data shall be record as per format provided in enclosed form c.0.2 of Annex


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C of this Code.

6.3.5 In case of measurement of shaft stress or strain, measurement and reading of testing

data shall be synchronous with horizontal displacement measurement.

6.4 Analysis and Determination of Measured Data

6.4.1 Measured data shall be cleared up according to the following requirements:

1. If unilateral multi-cycle loading method is adopted, horizontal force-time-action point

displacement )( 0Y t H −− relation curve and horizontal force-displacement gradient

)/( 0 H Y H ΔΔ− relation curve shall be drawn.

2. If low-speed maintenance load method is adopted, horizontal force, force action point

displacement 0Y H − relation curve, horizontal force vs displacement

gradient )/( 0 H Y H ΔΔ− relation curve, force action point displacement-time

logarithm )lg( 0 t Y − relation curve and horizontal force vs force action point

displacement double logarithmic )lg(lg 0Y H − relation curve.

3. Relation curve of proportion factor of horizontal reaction coefficients of horizontal force,

horizontal displacement of horizontal force action point vs foundation soil shall be

drawn )( 0 mY m H −− .

Pile top is free and action position of horizontal force is located on ground, m

value can be determined according to the following format:


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32

035

0

35

)(

).(

EI Y b

H vm y= 6.4.1-1

51

0

⎭⎬⎫

⎩⎨⎧=

EI mba 6.4.1-2

Where:

m ——Proportion factor of horizontal reaction coefficient on subgrade kN/m 4 ;

a ——Horizontal deformation coefficient m-1 of pile;

yν —— Horizontal displacement coefficient of pile top, α shall be calculated

according to formula 6.4.1-2 , when hα ≥ 4.0 h is buried depth of pile ,

yν =2.441;

H —— Horizontal force kN acting on the ground;

0Y ——horizontal displacement m of action point of horizontal force;

EI ——Bending rigidity kN · m2 of shaft; where, E is elastic modulus of shaft

material, I is moment of inertia of transformer section of shaft; 0b ——

calculation width of shaft m ; for annular pile: when pile diameter D ≤ 1m,

b=0.9 1.5 D+0.5 ; when pile diameter

D 1m, 0b = 0.9 D+1 . For rectangular pile: when margin B ≤ 1m, 0b =1.5 B+0.5;

when margin B 1m, 0b B+1.

6.4.2 The following curves shall be drawn for test embedded stress or strain measurement

sensor, and the corresponding data shall be listed in forms:1. Distribution graph of bending moment of shaft under action of horizontal force at each

level;


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2. Pulling/stress s H σ −

curve of horizontal force vs maximum bending moment section

reinforcement.

6.4.3 Horizontal critical load of single pile can be determined according to the following

methods:

1. Take the preceding level of the inflexion occurring on 0Y t H −− curve in case of

unilateral multi-cycle loading method or on 0Y H − curve in case of low-speed

maintenance load method.

2. Take horizontal load value corresponds to the first inflexion on

H Y H ΔΔ− /0 curve or 0lglg Y H − curve.

3. Take horizontal load value corresponds to the first inflexion on s H σ − curve.

6.4.4 Horizontal ultimate bearing capacity of single pile can be determined according to

the following methods:

1. Take horizontal load value corresponding to the preceding level of the inflexion

which drops sharply and obviously on 0Y t H −− curve in case of unilateral

multi-cycle loading method, or starting point which drops sharply and obviously on

0Y H − curve in case of low-speed maintenance load method.

2. Take horizontal load value of the preceding level of the place where obvious bend of

end of t Y lg0 − curve begins to occur in case of low-speed maintenance load

method.

3. Take horizontal load value, zontal load value corresponding to the second inflexion

on H Y H ΔΔ− /0 curve or 0lglg Y H − curve shall be taken.

4. Horizontal load value of previous level shall be taken when shaft breaks or tensioned


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reinforcement yields.

6.4.5 Horizontal ultimate bearing capacity and counting value of horizontal critical load of

single pile shall meet Clause 4.4.3 of this Code.

6.4.6 Determination of horizontal bearing capacity characteristic value of single pile in unit

job under same condition shall meet the following regulations:

1. When horizontal bearing capacity is controlled according to shaft strength, counting

value of horizontal critical load shall be taken as bearing capacity characteristic value

of single pile.

2. When pile receives long-term horizontal load action and is not allowed to be crack,

0.8 times of the counting value of horizontal critical load shall be taken as bearing

capacity characteristic value of single pile horizontal.

6.4.7 Besides Clause 6.4.6 of this Code, when horizontal bearing capacity is controlled

according to horizontal allowable displacement required by the design, horizontal load

corresponding to horizontal allowable displacement required by the design can be

taken as horizontal bearing capacity characteristic value of single pile, but the value

shall meet anti-crack design specified in relevant code.

6.4.8 The testing report shall include contents of Clause 3.5.5 in this Code, and shall also

include:

1 Geologic log of the testing pile;

2 Section size and reinforcement arrangement of the testing pile;

3 Load/unload method, load grading:

4 Curve and relevant data form required to be drawn by Clause 6.4.1;

5 Reference for determining the bearing capacity;

6 When reinforcement stress testing is carried out, and shaft bending moment is hence

calculated, sensor type, installation position, method for calculation of internal force,


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and curve and its relevant data form required to be drawn by Clause 6.4.2 shall be

available. .


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7. Core Drilling


7.1.1 This method is applicable for testing the pile length, shaft concrete strength, dreg

thickness of pile toe and shaft integrity of concrete filling pile, for the purpose of

determination or identification of rock and soil character of end bearing layer of pile.

7. 2 Equipment

7.2.1 Drilling machine operated by hydraulic pressure shall be used for taking core sample.

Instrument parameters of drilling machine shall meet the following regulations:

1. Rated maximum rotating speed is not lower than 790 min/r .

2. Scope for adjustment of rotating speed is less than 4 tier.

3. Rated working pressure shall not less than 1.5MPa.

7.2.2 Driller shall be equipped with single-action dual-duct driller and relevant orifice pipe,

underreamer, snap spring, posing stabilizer and driller than can take soft and loose

dregs out. Drilling pole shall smooth and straight, diameter shall be 50mm.

7.2.3 Drilling bit shall be diamond with proper granularity, concentration and matrix hardness

according to concrete design strength grade, and outer diameter shall not be less than

100 mm. Matrix of the drilling bit shall not have visual cracks, wany edge, corner


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shortage, inclination and bell mouth deformation.

7.2.4 Water discharge of water pump shall be 50 160 min/ L , pump pressure shall be

1.0-2.0 a Mp .

7.2.5 Saw used for sawing and cutting core sample shall have device for cooling the system

and for tightening the core sample, the matched diamond circular saw blade shall have

enough rigidity.

7.2.6 Screeder and planishing machine used for end surface of core sample shall meet

requirement for making the core sample .

7.3 On-the-Spot Operation

7.3.1 Core-drilling bore counts and core drilling position of each piece of the testing pile shall

meet the following regulations:

1. Pile with a pile diameter of less than 1.2m shall be drilled one bore, pile with pile

diameter of 1.2-1.6m shall be drilled two bores, pile with pile diameter of more

than1.6m shall be drilled three bores.

2. In case of one core-drilling bore, the bore shall be opened in a position 10-15 cm away

from pile center; In case of two or above core-drilling bores, the bore shall be opened

uniformly and symmetrically in a position 0.15-0.25D cm away from pile center

0.15-0.25D.

3. For drilling of end bearing layer of pile, each piece of the testing pile shall not be less

than one bore, and drilling depth shall meet design requirement.

7.3.2 Drilling instrument shall be installed correctly and firmly, pedestal shall be horizontal.


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Vertical shaft center of driller, head sheave center point of tangency of front edge of

overhead crane and orifice center must be on same plumb line. Operator shall ensure

that no inclination, displacement of driller will occur in core-drilling process,

deviation of verticality of core-drilling bore shall not be more than 0.5%.

7.3.3 When distance between pile top surface and driller pedestal is bigger, orifice pipe shall

be installed vertically and firmly.

7.3.4 In drilling process, circulating water flow in drilling bore shall not be interrupted,

drilling velocity shall be adjusted according to sand content and color of return water.

7.3.5 When core sample is taken by pulling out way, drilling bit and underreamer shall be

screwed and unloaded, core shall not be unloaded by hammering.

7.3.6 R ound trip meterage shall be controlled within 1.5m; when drilling to pile toe, dreg

shall be drilled and taken by using suitable core-drilling method and technology, and

then dreg thickness shall be determined, rock and soil character of end bearing layer of

pile shall be identified by suitable method.

7.3.7 The drilled core sample shall be placed into core sample box according to round trip

sequence from up to down , core sample with round trip quantity, block number, total

block quantity of this round trip shall be clearly indicated on side surface, and the

drilling situation and drilling abnormal situation shall be recorded timely according to

format of Form D.0.1-1 of Annex D of this Code, preliminary description shall be

made on core sample quality.

7.3.8 During core-drilling process, concrete of core sample, dreg of pile toe and end-bearing

layer of pile shall be recorded in details as per format of Form D.0.1-2 of Annex D of

this Code.

7.3.9 After core-drilling operation is finished, photos of core sample and marking board

marked with engineering name, pile number, core-drilling bore number, sampling


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position for core sample, pile length, bore depth, testing unit name shall be shot.

7.3.10 when quality appraisal of single pile meets the design, 0.5 1.0 a Mp pressure shall

be adopted, re-inject grout upwards from core-drilling bore bottom and seal off it;

otherwise, shall core-drilling bore shall be sealed off for treatment.

7 .4 Sampling and Processing of Core Sample

7.4.1 Concrete compression resistance core sample shall be taken according to the following

regulations:

1. When pile length is 10-30m, 3 groups of core samples shall be taken; when pile length

is less than 10m, 2 groups can be taken, when pile length is more than30m, not less

than 4 groups.

2. Distance between the upper core sample position and the designed elevation of pile top

shall not be more than one time of pile diameter or 1m, distance between the lower

core sample position and pile toe shall not be more than one time of pile diameter or

1m, middle core sample shall be taken in equal clearance.

3. When samples can be taken in defect position, a group of core samples shall be taken

for concrete compression resistance test.

4. When core-drilling bore quantity of same foundation pile is more than one, in which, if

one bore has defect at a certain depth, core sample shall be taken at this depth of other

bores for the purpose of concrete compression resistance test.

7.4.2 When pile end-bearing layer is middle weak weathering terrane and core can be made

into a test piece, a group of rock core samples shall be taken from nearby pile toe;


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Samples shall be done at each layer in case of delamination lithology.

7.4.3 Three core samples for compression resistance shall be made in each group of core

sample . Core sample shall be processed and measured according to Annex E of this

Code.

7. 5 Compressive Strength Test of Core Sample Test Piece

7.5.1 Compressive strength test can be executed immediately after fabrication of core

sample is finished.

7.5.2 Compressive strength test of concrete core sample shall be executed according to

current national standard-------C ommon Concrete Mechanical Property Test Method

GB/T50081 — 2002.

7.5.3 After compressive strength test, if average diameter of core sample is founded to be

less than 2 times of maximum grain diameter of concrete coarse aggregate in the test

piece, and if strength value is abnormal, strength value of this test piece shall not

participate in counting the average value.

7.5.4 Compressive strength of concrete core sample shall be calculated according to the

following:

2

4d p

f cu π ξ •= 7.5.4

Where cu f —compressive strength a Mp of concrete core sample, within accuracy of

0.1 a Mp ;

p —failure load ( N) measured by core sample compression resistance test;


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d —average diameter mm of core sample;

ξ —compressive strength conversion coefficient of concrete core sample shall

consider effect of core sample size, influence caused by core-drilling

machine on core sample disturbance and concrete mould condition through

determination of test counting; when no test counting data is available, value

shall be 1 .0 .

7.5.5 Monaxial compressive strength test of drill core of pile toe can be executed according

to current national standard---Construction Subgrade Foundation Design Code

(GB50007 —2002 Annex J).

7. 6 Analysis and Determination of Measured Data

7.6.1 Representative value of compressive strength of concrete core sample shall be

determined according to average value of strength value of a group of three test

pieces. In case of representative values of compressive strength of two groups or

above of concrete core samples in same depth part of same testing pile, its average

value shall be taken to be representative value of compressive strength of concrete

core sample in this depth of this pile.

7.6.2 The minimum value of representative value of compressive strength of concrete core

sample in different depth position in the testing pile is representative value of

compressive strength of concrete core sample of pile.

7.6.3 For end bearing layer character of pile, rock and soil characteristics of pile end bearing

layer of pile shall be determined according to characteristics of core sample,


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monoaxial compressive strength test of rock core sample, dynamic sound logging or

standard penetration test results , .

7.6.4 Shaft integrity type shall be determined according to core-drilling bore counts,

characteristics of concrete core sample on site, monoaxial compressive strength test

results of core sample, according to characteristics specified in Form 3.5.1 and Form

7.6.4 of this Code.

7.6.5 Appraisal of piling quality shall be executed according to single pile. In case of the

following circumstances, operator shall determine whether the following testing piles

are not meet design requirement:

1. Pile with type- Ⅳ shaft integrity.

2. Representative value of compressive strength of concrete core sample of the testing

pile shall be less than pile of concrete design strength grade.

3. Pile whose pile length and dreg thickness of pile toe do not meet design or this Code.

4. Pile whose soil character strength or thickness of end bearing layer of pile does not

meet design or this Code.


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Form 7.6.4 Determination of Shaft Integrity

Type Characteristics

Concrete core sample is continue, complete, smooth in surface, in good cementation, uniform

in aggregate distribution, in long column shape, anastomosing fracture, a small quantity of air

vents can be seen on side of core sample.

Concrete core sample is continue, complete, in good cementation, uniform in aggregate

distribution, in long column shape, approximately anastomosing fracture, honeycomb and

pockmarked face can be seen on partial of core sample side.

Ⅲ

A majority of concrete core sample is in good cementation, no loosening, or layered situation,

but one of the following situations can be seen:

Partial of core sample is broken and broken length is not more than 10cm

Not uniform in aggregate distribution of core sample;

Shortprismatic or massiveness situations of core sample;

Honeycomb and pockmarked face on side of core sample, grooves are connected together

Ⅳ

Difficult for drilling in;

Core sample breaks at random, slurry or layered stratum can be seen;

Partial core sample breaks and length of the broken part is more than 10cm

7.6.6 If core-drilling bore deviates pile, appraisal shall be only made on part which is used

for drilling the core sample.

7.6.7 Testing report shall include contents of Clause 3.5.5 of this Code, and shall include:

1. Core-drilling instrument;

2. Testing pile quantity, quantity of drilled bore, overhead, concrete core footage,

footage of drill core, total footage, group count of concrete test piece, group count of

rock test piece, dynamic sound logging or standard penetration test results ;

3. Histogram of each hole shall be drawn according to format in From D.0.1-3 of Annex


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D of this Code;

4. Monoaxial compressive strength test results of core sample;

5. Color pictures of core sample;

6. Statement of abnormal situation.


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8. Low Strain Integrity Testing


8.1.1 This method is applicable for testing the shaft integrity of concrete pile so as to

determine degree and position of shaft defect.

8.1.2 Effective testing pile length scope of this method shall be determined by on-the-spot

test.

8.2 Instrumentations

8.2.1 Main technical performance index of the testing instrumentations shall meet the

current industrial standard Dynamic Testing Instruments of Foundation Pile (JG/T3055)

and shall have functions of signal display, storage, treatment and analysis.

8.2.2 Transient state excitation instrument shall include hammer and pallet that can excite

broad pulse and spike pulse ; hammer can load force sensor; transient state excitation

instrument shall include electromagnetic steady state excitation with swept frequency

range of 10 2000 Hz and adjustable excitation force.


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8.3 On-the-Spot Inspection

8.3.1 The testing pile shall meet the following regulations:

1. Shaft strength shall meet paragraph of Clause 3 .2.6 of this Code.

2. For material of pile head, strength, section size shall be approximately same with

shaft.

3. Pile top surface shall flat, smooth, dense, and shall be approximately vertical with pile

axes.

8.3.2 Setting of testing parameters shall meet the following regulations:

1. Time quantum length recorded by time domain signal shall not be less than 5 ms after

2 c L / ; upper limit of frequency scope analyzed by amplitude frequency signal shall

not be less than 2000 Hz .

2. The preset pile length shall be length from survey point of pile top to construction pile

of pile toe, the preset shaft section area shall be construction section area.

3. Shaft wave velocity can be set preliminarily according to testing value of same type

of pile in local region.

4. The sampling time interval or sampling frequency shall be set according to pile length,

shaft wave velocity and frequency domain resolution shall be chosen reasonably;

sampling point of time domain signal shall not be less than 1024 points.

5. Preset value of sensor shall be set according to results of metrological verification .

8.3.3 Installation of measurement sensor and excitation operation shall meet the following

regulations:

1. Installation of sensor shall be vertical with pile top surface; and the sensor shall have

enough binding strength if sensor is bound by using couplant.


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2. Excitation point position of solid pile shall be chosen at pile center, measurement

sensor installation position shall be 2/3 of radius of pile center; excitation point of

hollow pile and installation position of measuring sensor shall be on same horizontal

surface, inclination between this surface and the connecting line of pile center shall be

90° , excitation point and installation position of the measuring sensor shall be 1/2 of

thickness of pile wall.

3. Excitation point and installation position of the measuring sensor shall be free of

influence of main reinforcement of reinforcement cage.

4. Excitation direction shall be pile axes direction.

5. Transient state excitation shall be subject to on-the-spot tap test, operator shall choose

excitation hammer and pallet with proper weight, and shall obtain pile toe or defect

echo signal at lower part of shaft by using broad pulse, and shall obtain defect echo

signal at higher part of shaft by using spike pulse.

6. For excitation of steady state, operator shall obtain stable response signal under each

preset frequency, and shall adjust excitation force according to pile diameter, pile

length and pile soil restrain.

8.3.4 Collection and screening of signal shall meet the following regulations:

1. According to pile diameter, 2-4 testing points shall be arranged at pile center

symmetrically; valid signal counts recorded by each testing point shall not be less than

3.

2. Check and judge whether the actually-measured signals have reflected shaft integrity

characteristics.

3. Consistency between different testing points and time domain signal measured after

many times is poorer, operator shall analyze reason and increase testing point quantity.

4. Distortion and null shift of signal shall be avoided, signal value shall not be more than


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range of measurement system.

8.4 Analysis and Determination of Measured Data

8.4.1 Determination of average value of wave velocity of shaft shall meet the following

regulations:

1. When pile length has been known and echo signal of pile toe is explicated, in

foundation pile with same geographical conditions, design pile type and piling

technology, operator shall choose shaft wave velocity value of type-I pile of not less

than 5 pieces, its average value shall be calculated according to the following formula:

n

iim cn

c1

1

=∑= c 8.4.1-1

T L

c i Δ= 200 8.4.1-2

f Lc i Δ•= 2 8.4.1-3

Where mc ——average value m/s of shaft wave velocity ;

ic ——shaft wave velocity value m/s of No. i piece of the testing pile, and

mmi ccc /− ≤ 5%

L —— pile length m under survey point;

T Δ ——Time difference ms between the first peak of velocity wave and echo

wave peak of pile toe;

f Δ —— frequency difference Hz between neighboring resonance peaks of pile


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toe on amplitude frequency curve ;

n ——foundation pile quantity n ≥ 5 participate in calculation of average

value of wave velocity.

2. When the value cannot be determined according to the aforesaid clause, average value

of wave velocity can be determined according to actually-measured value of same pile

type and piling technology in local region in other pile foundation works with the

same pile type and piling technology in local region, and according to aggregate

variety and strength grade of shaft concrete.

8.4.2 Shaft defect position shall be calculated according to the following formula:

ct x x •Δ•= 20001

8.4.2-1

/21

f c

x Δ•= 8.4.2-2

Where x ——distance m) between shaft defect and sensor installation point;

. xt Δ —— time difference m between the first peak of velocity wave and defect echo

wave peak;

c ——shaft wave velocity m/s) of the testing pile can be substituted by c value if the

value cannot be determined.

/ f Δ ——frequency difference Hz between neighboring defect resonance peaks on

amplitude frequency on signal curve.

8.4.3 For shaft integrity type, attenuation characteristic of signal, designed pile type, piling

technology, geographical conditions, construction circumstance shall be tested

according to depth of defect, and shall be analyzed and determined according to

actually measured time domain or amplitude frequency signal characteristics

stipulated in Clause 3.5.1 and Form 8.4.3 of this Code.


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Form 8.4.3 Determination of Shaft Integrity

Type Signal characteristics of time domain Amplitude frequency signal

characteristics

Before the time of 2 c L / , there is no defect echo wave, pile toe

echo wave is available.

Clearance of joint array of column

base, its neighboring frequency

difference Lc f 2/≈Δ Before the time of 2 c L / , slight defect echo wave occurs, and pile

toe echo wave is available.

Clearance of resonance peak array of

pile toe is approximately equal, its

neighboring frequency difference is as

follows: Lc f 2/≈Δ , frequencydifference between resonance peak

arising from slight defect and resonance

peak of pile toe is as follows:

Lc f 2// fΔ Ⅲ With obvious defect echo wave, other characteristics are between type Ⅱ and Ⅳ .

Ⅳ Before 2 c L / serious defect echo wave or cycle echo wave

occur, there is no pile toe echo wave;

or serious defect of shallow part of column makes wave shape

show low frequency large-amplitude damped vibration, there is no

pile toe echo wave.

Clearance of defect resonance peak

array is approximately equal,

neighboring frequency difference

shall be as

follows Lc f 2// fΔ ,there is no piletoe resonance peak; .

or serious defect at shallow part of

column is that only single resonance

peak occurs, there is no pile toe

resonance peak.

Note: For foundation pile with same site, similar geographical conditions, pile type and piling technology, when no pile toe

echo wave occurs in actually measured signal due to impedance of shaft and impedance of bearing stratum of pile end, shaft

integrity type with pile toe echo wave can be determined according to other piles with actually-measured signals under same

conditions of this site.


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8.4.4 For concrete filling pile, when time domain signal is used for analysis, after shaft

section change gradually, it restores to primary echo at sudden change position of

impedance of the original pile diameter, or secondary echo at sudden change position

of diameter expansion, determine integrity type of the testing pile according to

analysis piling technology and geographical conditions. If necessary,

actually-measured curve can be adopted for legal assistance in determination of shaft

integrity or in virtue of admittance value, relative high-low assistant determine shaft

integrity of dynamic rigidity.

8.4.5 For rock-socketed pile, when time domain echo signal of pile toe is single echo wave

and has same direction with hammering impulse signal, other methods shall be

adopted for verification of rock-socketed situation of pile end.

8.4.6 In case of the following circumstances, shaft integrity shall be determined according

to other testing method:

1 Actually measured signals are complicated and has no rule, so exact appraisal on it

cannot be available..

2 Concrete filling pile with gradual or frequent large changes of shaft section.

8.4.7 Low strain testing report shall provide actually measured signal curve of shaft

integrity testing.

8.4.8 The testing report shall include Clause 3.5.5 of this Code and shall also include the

following:

1 Value of shaft wave velocity;

2 Shaft integrity description, defect position and shaft integrity type;

3 Measuring scale of shaft length, index or linear amplification scope and multiple

in time domain signal period; or frequency scope for analysis of amplitudefrequency signal curve, pile toe or frequency difference among neighboring

resonance peaks corresponding to shaft defect.


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9. High Strain Dynamic Testing


9.1.1 The method is applicable to measurement of vertical bearing capacity of the foundation

Technical Code for Testing of Building Foundation Piles

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